Spook got called back by the brass. He takes orders from above.
Discussion
Is his book classified information? I just thought we had a first amendment or something.
He is a national military operative, and if his book in any way was bad optics or revealed an unsavoury criticism of the American military establishment, they needed only tug on his leash and he would have to come home. So he did. He need not say more, nor is he allowed too. I'm sure he's disappointed, but a military man has a chain of command.